Large Model Association Forum

Hi Alan The wings will be folders (probably electric for the first fold with a pushrod /bellcrank set-up to fold the tips). The inner section will carry the linkage for the Youngman (Fairey) flaps - on the full-size, they hinge /extend from a cantilevered arm off the rear spar /trailing edge. The ou...

Hi All Just read Alan Cantwell's thread on Washout - very informative... I'm wondering about how best to deploy it on the 1/4 scale Wyvern which has a double wing-fold. The first fold occurs at about 1/4 span and, although the wing bottom is horizontal, it has 1 degree of anhedral due to spanwise ta...

Hello David. Nice to see another Wyvern engineer-pilot in the making ! I'm just convalescing from a hospital op' and last week read Harald Penrose's autobiography - chief test pilot for Westlands (he did a lot of the original test /development work on the Eagle, Clyde and Python variants). I've also...

Alan's got a good point there. What with the price of fuel, postage, etc these days, it may be beyond economical repair. So, perhaps, strip it down for spares. However, if your model is prone to banging its tailwheel down hard, it may be wise to fit a metal output gear rather than a nylon one which ...

I worked on Gannets in the FAA - 849 squadron based at Brawdy, S.Wales. Strictly speaking, these are co-axial units due to the Double Mamba's twin turbines /separate gearboxes. There is a beginning thread for my build on 'Your New Projects' but no photos as yet. All my gears are mocked up in wood at...

Hi Richard I'm based near Malmesbury, Wilts. Is your problem electronics or mechanical ? I'm currently designing /building a 1/4 scale contra-prop gearbox for my Wyvern project, so this is of interest. I'm not sure what the position is regarding Futaba spares though...I've just located a good suppli...

I'm pleased to say that this project is now registered (Over 20Kg category), and, is finally underway. No quarter-scale documentation has been found so far, so, I expect that everything will have to be adapted from other scales. This may mean that I'll have to teach myself CAD ! (Normally, I'm more ...

All - thanks for the many contributions to this. My conclusion is that the project is feasible at 1/4 scale but will be very demanding of time, resources etc. and, I think a 3-5 year timescale may be necessary to sort out the detailed engineering issues. Progress so far includes an in-depth look at ...

Cheers Barrie - very helpful that. I'm now in touch with Mike Murphy (Wren Turbines) and Dave Wigley of New York (designer/builder of the 1/5th 'S4' prototype that won Top Gun). Also, Phil Clark (Fighter Aces) has offered help on the materials supply side. On the fuel front, do you get any trim chan...

Hi again Barrie, Just a few questions at this stage : any experience with running the jet pipe exists down the inside of the fuselage on any of your above models ? (The JP exists on the Wyvern are just above the wing trailing edges for true scale effect). Secondly, what's the largest prop size /no.o...

Hi All I'm planning a new turbo-prop project ( Westland Wyvern ) - see "Technical Help" forum for further details. Would be interested to know if anyone has experience with any of the current commercial offerings - Jetcat, Wren etc ? Also, I'm aware of a few 'home-built' turbo projects on ...

Hi Phil - thanks. I may well need to talk to him at some point. I think I saw an ad' for his plan somewhere ? Been discussing powertrain ideas with Wren Turbines this week. Am currently working on design ideas for the contra-prop gearbox and variable pitch units. If I were to go for 1/4 scale would ...

Thanks Barrie and Chris. I will pursue these contacts when time permits. (I've just had a request for a painting of Jim Clark's Lotus 33 for a birthday present, so, will have to do some research on that asap !). Yes, the Bearcat is indeed a magnificent piece of model engineering. I think the designe...

Thanks Barrie - I found a video of this one on Youtube but it's nice to have some tech' as well from the magazine source. A very impressive model indeed. I see he's neatly 'side-stepped' the contra-prop drive issue by making on of them a free-wheeling unit. I suspect he's not bothered with variable ...

Thanks for the advice and encouragement Stewart. The thinking on the props was that as they would need a reduction gearbox anyway, I could add a (reversing) co-axial shaft drive plus some fly-weights to operate the pitch change. There is, of course, the problem of the dreaded inter-shaft bearing to ...

Hi all. Not sure if I'm on the right forum but here goes:- I'm ex-Fleet Air Arm (engineering) and would like to attempt an advanced Westland Wyvern project. Main design preferences to include a working turbo-prop unit (with contra-props), double wing-fold, full retracts, lowering deck hook and torpe...

Hi - just been consulting some of my Flight Physics colleagues here at Airbus... A CG of between 25% and 32% of chord would seem a sensible range for this class of model. However, someone mentioned the use of flaps. This will alter the relative CG to CP (Centre-of-Pressure) position on take-off and ...